1. Technical Field
The present invention relates to a technology that controls an amount of transportation of a recording medium in transporting the recording medium.
2. Related Art
In JP-A-2001-054957, a configuration is disclosed in which the recording medium is transported using two transportation rollers. Specifically, a nip roller is provided with respect to each of the two transportation rollers that are in parallel with each other along a transportation path for the recording medium. Then, rotation of each transportation roller makes the recording medium be transported while the recording medium is interposed between each transportation roller and the nip roller. At this time, control of the amount of transportation of the recording medium is executed by counting drive pulses of a motor that drives the transportation roller.
In other words, in JP-A-2001-054957, it is disclosed that the amount of rotation of the transportation roller is set to reflect an amount of transportation of the recording medium, and the amount of transportation of the recording medium is controlled based on a counter value of the drive pulse that correlates with an amount of rotation of the transportation roller. However, because slipping easily occurs between the transportation roller and the recording medium, which are described above, it is practically difficult to precisely control the amount of transportation of the recording medium based on the counter value of the drive pulse. This respect is described in detail as follows.
The recording medium receives a force from the transportation roller and thus is transported. Therefore, it is necessary to rotate the transportation roller in a state where the force appropriately is transferred from the transportation roller to the recording medium, in order to transport the recording medium with the amount of transportation according to the amount of rotation of the transportation roller. However, the great drive force given by the motor is not always appropriately transferred from the transportation roller to the recording medium, and there are cases where the slipping occurs between the transportation roller and the recording medium. For this reason, it is difficult to control precise control of the amount of transportation of the recording medium based on the counter value of the drive pulse.